US Patent 7688193 Oil level detection device for internal combustion engine

An oil level detection device for an internal combustion engine, which comprises: a housing permitting entry therein of oil; a float provided within the housing and vertically movable with the oil entered in the housing; a switch for performing switching operation in response to the vertical movement of the float within the housing; protrusions provided, on the upper surface of the float, for preventing the float from sticking to the ceiling of the housing due to viscosity of the oil; and protrusions provided, on the bottom of the housing, for preventing the float from sticking to the bottom of the housing due to viscosity of the oil.